GRAPHALLOY ^®

Molten Sulfur Pump Vibration is No Match for
GRAPHALLOY Iron-Grade Bearings

At a major refinery, vertical molten sulfur pumps were fitted with nickel-chromium (Ni-Cr) bearings to handle the high-temperature environment.  To avoid seizing and galling, the line shaft and volute bearings were fit with 0.020 – 0.025” running clearance. However, the pumps were experiencing high vibration, approaching 1.0 inches/second peak. When they disassembled the pump, the bearing clearances had opened up to 0.030 – 0.034”.

The customer contacted one of our engineers and asked:
"How well do the GRAPHALLOY sleeve bearings fare in liquid sulfur service? There are eight vertical column pumps in our sulfur pit..four of which are quite the trouble-makers when it comes to high vibration. Vibration data usually indicates some sort of imbalance. Any feedback is greatly appreciated as this definitely sounds like a product worth pursuing to "dampen" the current vibration in these pumps."

The pump was rebuilt using GRAPHALLOY Iron-Grade Bearings with a shaft to bushing clearance of 0.006 – 0.007”.  The tighter clearances were possible due to the non-galling properties of GRAPHALLOY.

The overall high vibration level decreased to a maximum of 0.21 inches/second peak.  The pump worked so well that the refinery has since rebuilt three additional pumps to the same standards using GRAPHALLOY Iron-Grade Bearings.

Key Features:

• Self-Lubricating: Graphalloy is lubricated by the pumpage and needs no additional lubrication. Runs dry and keeps on running.
• Non-Galling: Permits closer running clearances between rotating parts resulting in lower shaft vibration. Survives high speed contact that would gall metal parts.
• Wide Temperature Range: -400°F to 750°F (-254°C to 400°C)
• Submerged: Maintains dimensional stability when submerged under load and over wide temperature swings. Provides constant running clearances. Won’t Swell.

9/1/2018